Accommodating intraocular lens system having spherical aberration compensation and method

ABSTRACT

An accommodating intraocular lens includes an optic portion, a haptic portion. The optic portion of the lens includes an actuator that deflects a lens element to alter the optical power of the lens responsive to forces applied to the haptic portion of the lens by contraction of the ciliary muscles and a secondary deflection mechanism. Movement of the lens element by the actuator causes the lens element to deform and the secondary deflection mechanism causes the lens to further deform.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. application Ser. No.13/193,983, filed Jul. 29, 2011, which is a continuation of U.S.application Ser. No. 12/177,857, filed Jul. 22, 2008, now U.S. Pat. No.8,328,869, which is a continuation-in-part of U.S. application Ser. No.11/646,913, filed Dec. 27, 2006, now U.S. Pat. No. 7,637,947, all ofwhich are incorporated by reference herein;

Said U.S. application Ser. No. 12/177,857, filed Jul. 22, 2008, alsoclaims the benefit of the filing date of U.S. Provisional ApplicationNo. 60/951,441, filed Jul. 23, 2007, the disclosure of which isincorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to intraocular lenses (“IOLs”) havingoptical parameters that are changeable in-situ. More particularly, theinvention has application in IDLs for in-capsule implantation forcataract patients or presbyopic patients, wherein movement of the lenscapsule applies forces to a circumferentially supported haptic to moreefficiently induce transfer of fluid media within the interior of theIOL to alter an optical power of the lens.

BACKGROUND OF THE INVENTION

Cataracts are a major cause of blindness in the world and the mostprevalent ocular disease. Visual disability from cataracts accounts formore than 8 million physician office visits per year. When thedisability from cataracts affects or alters an individual's activitiesof daily living, surgical lens removal with intraocular lens (IOL)implantation is the preferred method of treating the functionallimitations. In the United States, about 2.5 million cataract surgicalprocedures are performed annually, making it the most common surgery forAmericans over the age of 65. About 97 percent of cataract surgerypatients receive intraocular lens implants, with the annual costs forcataract surgery and associated care in the United States being upwardsof $4 billion.

A cataract is any opacity of a patient's lens, whether it is a localizedopacity or a diffuse general loss of transparency. To be clinicallysignificant, however, the cataract must cause a significant reduction invisual acuity or a functional impairment. A cataract occurs as a resultof aging or secondary to hereditary factors, trauma, inflammation,metabolic or nutritional disorders, or radiation. Age related cataractconditions are the most common.

In treating a cataract, the surgeon removes the crystalline lens matrixfrom the lens capsule and replaces it with an intraocular lens (“IOL”)implant. The typical IOL provides a selected focal length that allowsthe patient to have fairly good distance vision. Since the lens can nolonger accommodate, however, the patient typically needs glasses forreading.

More specifically, the imaging properties of the human eye arefacilitated by several optical interfaces. A healthy youthful human eyehas a total power of approximately 59 diopters, with the anteriorsurface of the cornea (e.g., the exterior surface, including the tearlayer) providing about 48 diopters of power, while the posterior surfaceprovides about −4 diopters. The crystalline lens, which is situatedposterior of the pupil in a transparent elastic capsule, also referredto herein as “capsular sac,” supported by the ciliary muscles viazonules, provides about 15 diopters of power, and also performs thecritical function of focusing images upon the retina. This focusingability, referred to as “accommodation,” enables imaging of objects atvarious distances.

The power of the lens in a youthful eye can be adjusted from 15 dioptersto about 29 diopters by adjusting the shape of the lens from amoderately convex shape to a highly convex shape. The mechanismgenerally accepted to cause this adjustment is that ciliary musclessupporting the capsule (and the lens contained therein) move between arelaxed state (corresponding to the moderately convex shape) and acontracted state (corresponding to the highly convex shape). Because thelens itself is composed of viscous, gelatinous transparent fibers,arranged in an “onion-like” layered structure, forces applied to thecapsule by the ciliary muscles via the zonules cause the lens to changeshape.

Isolated from the eye, the relaxed capsule and lens take on a morespherical shape. Within the eye, however, the capsule is connectedaround its circumference by approximately 70 tiny ligament fibers to theciliary muscles, which in turn are attached to an inner surface of theeyeball. The ciliary muscles that support the lens and capsule thereforeare believed to act in a sphincter-muscular mode. Accordingly, when theciliary muscles are relaxed, the capsule and lens are pulled about thecircumference to a larger diameter, thereby flattening the lens, whereaswhen the ciliary muscles are contracted the lens and capsule relaxsomewhat and assume a smaller diameter that approaches a more sphericalshape.

As noted above, the youthful eye has approximately 14 diopters ofaccommodation. As a person ages, the lens hardens and becomes lesselastic, so that by about age 45-50, accommodation is reduced to about 2diopters. At a later age the lens may be considered to benon-accommodating, a condition known as “presbyopia”. Because theimaging distance is fixed, presbyopia typically entails the need forbifocals to facilitate near and far vision.

Apart from age-related loss of accommodation ability, such loss isinnate to the placement of IOLs for the treatment of cataracts. IOLs aregenerally single element lenses made from a suitable polymer material,such as acrylics or silicones. After placement, accommodation is nolonger possible, although this ability is typically already lost forpersons receiving an IOL. There is significant need to provide foraccommodation in IOL products so that IOL recipients will haveaccommodating ability.

Although previously known workers in the field of accommodating IOLshave made some progress, the relative complexity of the methods andapparatus developed to date have prevented widespread commercializationof such devices. Previously known devices have proved too complex to bepractical to construct or have achieved only limited success, due to theinability to provide accommodation of more than 1-2 diopters.

U.S. Pat. No. 5,443,506 to Garabet describes an accommodatingfluid-filled lens wherein electrical potentials generated by contractionof the ciliary muscles cause changes in the index of refraction of fluidcarried within a central optic portion. U.S. Pat. No. 4,816,031 to Pfoffdiscloses an IOL with a hard poly methyl methacrylate (PMMA) lensseparated by a single chamber from a flexible thin lens layer that usesmicrofluid pumps to vary a volume of fluid between the PMMA lens portionand the thin layer portion and provide accommodation. U.S. Pat. No.4,932,966 to Christie et al. discloses an intraocular lens comprising athin flexible layer sealed along its periphery to a support layer,wherein forces applied to fluid reservoirs in the haptics vary a volumeof fluid between the layers to provide accommodation.

Although fluid-actuated mechanisms such as described in theaforementioned patents have been investigated, currently availableaccommodating lenses include the Crystalens developed by Eyeonics, Inc.(formerly C&C Vision, Inc.) of Aliso Viejo, Calif. According toEyeonics, redistribution of the ciliary mass upon constriction causesincreased vitreous pressure resulting in forward movement of the lens.

Commonly assigned U.S. Publication No. 2005/0119740 to Esch et al., nowU.S. Pat. No. 7,261,737, which is incorporated by reference herein inits entirety, describes an intraocular lens in which forces applied bythe lens capsule to a haptic portion of the lens to induce fluidtransfer to and from an actuator disposed in contact with a dynamicsurface of the lens.

Another disadvantage of previously known devices is that they oftentimescreate spherical aberrations. As is well known in the art, lensescomposed of elements having spherical surfaces are easy to manufacturebut are not ideal for creating a sharp image because light passingthrough the elements does not focus on a single focal point. Inparticular, light that passes through a positive optical element closeto the optical axis generally converges at a focal point that is furtherfrom the lens than a focal point of light passing through the peripheralportion of the lens, thereby creating under corrected sphericalaberration. As a result of spherical aberration in an intraocular lens,all of the light passing through the lens does not focus on the retinaresulting in an image that may be blurred and may have softenedcontrast.

Various devices have been used in optical systems to reduce the effectof spherical aberration. For example, an aperture may be used thatlimits the ability of light to pass through the peripheral portion ofthe lens. As a result, the light contributing to the aberration isprevented from passing through the lens. Such a device provides anobvious disadvantage that the amount of light allowed to pass throughthe lens is reduced. Another way to reduce the effect of sphericalaberration is to combine two lenses, one convex and one concave. A stillfurther method of reducing the effects of spherical aberration is to usean aspherical lens. However, such combined lenses and lenses havingaspherical profiles are significantly more expensive to produce. Inaddition, combining lenses requires additional space to house themultiple lenses.

While the lens described in the foregoing Esch application is expectedto provide significant benefits over previously-known accommodating lensdesigns, it would be desirable to provide methods and apparatus forfurther enhancing conversion of lens capsule movements into hydraulicforces, so as to improve modulation of the lens actuator and dynamicsurface.

It also would be desirable to provide methods and apparatus to enhancethe efficiency with which loads arising due to natural accommodatingmuscular action are converted to hydraulic forces.

It also would be desirable to provide methods and apparatus that reducespherical aberration while maximizing the useful surface area of anaccommodating lens design.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide apparatus and methods that restore appropriate optical focusingpower action to the human eye.

It is a further object of this invention to provide methods andapparatus wherein a dynamic lens surface may be hydraulicallymanipulated responsive to movement of the ciliary muscles and lenscapsule.

It also is an object of the present invention to provide methods andapparatus for further enhancing conversion of lens capsule movementsinto hydraulic forces, so as to improve modulation of the lens actuatorand dynamic surface.

It is another object of this invention to provide methods and apparatusto enhance the efficiency with which loads arising due to naturalaccommodating muscular action are converted to hydraulic forces.

It is another object of this invention to provide methods and apparatusfor reducing spherical aberration in an accommodating intraocular lensdevice.

These and other objects of the present invention are accomplished byproviding an intraocular lens responsive to forces communicated from theciliary muscles through the zonules to the capsular bag to operate oneor more actuators disposed within the IOL. The actuator is coupled to adynamic surface of the IOL to deflect the dynamic surface, e.g., from amoderately convex to a highly convex shape, responsive to operation ofthe one or more actuators. In accordance with the principles of thepresent invention, the IOL includes at least one secondary deflectionmechanism that is configured to further alter the curvature of thedynamic surface to correct for spherical aberration. The secondarydeflection mechanism may be alterations of the lens such as varyingthickness or inflection points, selection of the boundary condition ofthe lens, and secondary fluid-mediated actuators.

In an embodiment, the secondary deflection mechanism is a fluid-mediatedactuator coupled to a fluid column disposed in at least one haptic ofthe IOL and a sealed fluid cavity filled with shaping fluid that isadjacent to the dynamic surface. Forces applied to the haptic by thecapsular bag, responsive to movement of the ciliary muscles, cause thetransfer of fluid between the fluid column and the actuator, which inturn deflects a dynamic surface of the lens.

Deflection of the dynamic surface causes the shaping fluid in the sealedfluid cavity to redistribute which, in turn, alters the shape of thedynamic surface so that it is aspherical. By making the dynamic surfaceaspherical the total amount of travel required by the actuator may bereduced from approximately 300 microns for non-aspheric lenses to 200microns. As a result, a more efficient IOL may be produced that requiresless influence from the lens capsule.

In a preferred embodiment, the intraocular lens comprises an opticportion including a fluid cavity containing a fixed volume of shapingfluid and a haptic (or non-optic) portion. The optic portion comprises alight transmissive substrate defining one or more fluid channels, atleast one actuator coupled in fluid communication with the fluidchannels, and anterior and posterior lens elements. At least one of theanterior and posterior lens elements includes a dynamic surface that isoperatively coupled to the actuator to cause deflection of the dynamicsurface. The other of the anterior or posterior lens elements may becoupled to the substrate or integrally formed therewith.

The haptic portion is disposed at the periphery of the optic portion andcomprises one or more haptics that extend outward from the opticportion, each haptic including a fluid channel coupled in fluidcommunication with a fluid channel in the optic portion. In accordancewith one aspect of the present invention, the haptics have across-sectional configuration selected so that the internal volume ofthe haptic is small in an accommodated state. The accommodated state ofthe haptic is selected to correspond to the accommodated state of theeye, when the ciliary muscles are contracted and anterior/posteriorcompressive forces applied by the capsular bag to the haptics arereduced.

When the ciliary muscles relax, the zonules pull the capsular sac tautand apply forces to the anterior and posterior faces of the haptic. Theforces applied by the capsular sac cause the cross-sectional area of thehaptic to increase thereby increasing the internal volume of the haptic.This action in turn causes fluid to be withdrawn from the actuatordisposed in the optic portion, so that the dynamic surface of the IOLtransitions from an accommodated state to an unaccommodated state. Thefixed volume of shaping fluid in the sealed fluid cavity isredistributed in the cavity by movement of the dynamic surface and thatredistribution causes the shape of the dynamic surface to be altered.

The actuator used in the optic portion of the IOL may be centrallylocated within the optic portion that, when filled with fluid, biasesthe dynamic surface of the IOL to the accommodated state. When theciliary muscles are contracted, the zonules and capsular bag are lesstaut, and the haptics are unstressed. Relaxation of the ciliary musclecauses the zonules to transition the capsule to less convex shape, whichapplies compressive forces to the haptic, thereby withdrawing fluid fromthe actuator and causing the lens to transition to the unaccommodatedstate. Alternatively, the actuator may comprise structures disposed atthe periphery of the optic portion, so as to further minimize refractiveeffects and optical aberrations in the optic portion.

Methods of making and using the lens of the present invention also areprovided.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments, in which:

FIG. 1 is a sectional side view of a human eye;

FIGS. 2A and 2B are, respectively, sectional side views of the lens andsupporting structures of FIG. 1 illustrating relaxed and contractedstates of the ciliary muscles;

FIG. 3 is another sectional side view of a human eye illustrating lightpassing through a spherical lens in the lens capsule;

FIGS. 4A-4C are, respectively, a perspective, exploded perspective andplan view of an exemplary intraocular lens which may be modified toimplement the structure and methods of the present invention;

FIG. 5 is a cross-sectional view of a haptic of the intraocular lens ofFIG. 4;

FIG. 6 is a cross-sectional view of the assembled intraocular lens ofFIG. 4;

FIGS. 7A, 7B and 7C are, respectively, cross-sectional views of anintraocular lens optic portion in unaccommodated (FIGS. 7A and 7B), andaccommodated configurations (FIG. 7C);

FIGS. 8A and 8B are, respectively, a perspective view and across-sectional view of an illustrative embodiment of the intraocularlens of the present invention;

FIGS. 9A and 9B are, respectively, a perspective view and across-sectional view of an alternative embodiment of the intraocularlens of the present invention;

FIGS. 10A and 10B are, respectively, a perspective view and across-sectional view of an alternative embodiment of the intraocularlens of the present invention;

FIGS. 11A and 11B are, respectively, a perspective view and across-sectional view of an alternative embodiment of the intraocularlens of the present invention; and

FIG. 12 is a perspective view of an alternative embodiment of theintraocular lens of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the principles of the present invention, anintraocular lens is provided having a haptic portion and alight-transmissive optic portion. The optic portion contains one or morefluid-mediated actuators arranged to apply a deflecting force on adynamic surface of the lens to provide accommodation. As used herein,the lens is fully “accommodated” when it assumes its most highly convexshape, and fully “unaccommodated” when it assumes its most flattened,least convex state. The lens of the present invention is capable ofdynamically assuming any desired degree of accommodation between thefully accommodated state and fully unaccommodated state responsive tomovement of the ciliary muscles and lens capsule.

Furthermore, in accordance with the principles of the present inventionthe optic portion contains one or more secondary deflection mechanismthat alters the curvature of the lens. For example, the secondarydeflection mechanism may be sealed fluid cavities that are filled with aconstant volume of shaping fluid that is redistributed when the lens isactuated between the accommodated and unaccommodated states. As will bediscussed in further detail below, when a fluid-mediated actuatorapplies a deflecting force on a portion of the dynamic surface it causesa portion of a sealed fluid cavity to change in volume. However, becausethe volume of fluid is fixed, the change in volume in one portion of thecavity causes a complimentary change in volume of another portion,whereby one portion of the dynamic surface becomes more convex at adifferent rate than another portion. The secondary deflection mechanismalso may be integrated into the lens, such as varying thickness orinflection points or areas. As a further alternative, the secondarydeflection mechanism may be a boundary condition, i.e., characteristicsof the connection of the lens to the remainder of the optic portionaround the circumference. As a result of the one or more secondarydeflection mechanism, the dynamic surface may be deflected into anaspheric profile, which may be used to correct spherical aberration.

Referring to FIGS. 1 and 2, the structure and operation of a human eyeare first described as context for the present invention. Eye 10includes cornea 11, iris 12, ciliary muscles 13, ligament fibers orzonules 14, capsule 15, lens 16 and retina 17. Natural lens 16 iscomposed of viscous, gelatinous transparent fibers, arranged in an“onion-like” layered structure, and is disposed in transparent elasticcapsule 15. Capsule 15 is joined by zonules 14 around its circumferenceto ciliary muscles 13, which are in turn attached to the inner surfaceof eye 10. Vitreous 18 is a highly viscous, transparent fluid that fillsthe center of eye 10.

Isolated from the eye, the relaxed capsule and lens take on a convexshape. However, when suspended within the eye by zonules 14, capsule 15moves between a moderately convex shape (when the ciliary muscles arerelaxed) and a highly convex shape (when the ciliary muscles arecontracted). As depicted in FIG. 2A, when ciliary muscles 13 relax,capsule 15 and lens 16 are pulled about the circumference, therebyflattening the lens. As depicted in FIG. 2B, when ciliary muscles 13contract, capsule 15 and lens 16 relax and become thicker. This allowsthe lens and capsule to assume a more convex shape, thus increasing thediopter power of the lens.

Additionally, various natural mechanisms affect the design requirementsof the present invention. For example, during accommodation the pupilnaturally stops down (i.e., reduces in diameter) which reduces the areaof the natural lens that transmits light. In addition, the eye willexperience the Stiles-Crawford Effect which also reduces the effectivearea of the natural lens. In particular, the brightness of light raysincident on cones in the eye is dependent on the angle at which thoserays are incident on the cones. In particular, light rays that strikethe cones perpendicular to their surface appear brighter than those thatdo not. As a result, the light rays passing through the periphery of thelens are less significant for proper vision.

Accommodating lenses that are currently commercially available, such asthe Crystalens device developed by Eyeonics, Inc., Aliso Viejo, Calif.,typically involve converting movements of the ciliary muscle intoanterior and posterior translation of an optic portion of the IOLrelative to the retina. Such devices do not employ the naturalaccommodation mechanisms described above with respect to FIGS. 1-2, butinstead rely directly on changes in vitreous pressure to translate thelens.

Referring now to FIG. 3, a simplified schematic is provided of thespherical aberration effects of implanting spherical lens 19 withincapsule 15 thereby introducing spherical aberrations. In particular,light rays L passing through a central portion of spherical lens 19,i.e., near the optical axis, converge at location A on retina 17.However, light rays L passing through the peripheral portion ofspherical lens 19 converge at location B which is spaced from location Aand retina 17. Because location B is spaced from retina 17, when thoselight rays reach retina 17 they are dispersed. Although only two focalpoints are illustrated in FIG. 3, it should be appreciated that lightrays passing through lens 19 will focus at many different focal pointsalong the optical axis of the lens and the distance of any particularfocal point from retina 17 depends on the radial location on lensthrough which the light rays pass.

Referring now to FIGS. 4-6, an exemplary embodiment of an intraocularlens suitable for implementing the structure of the present invention isdescribed, such as is described in the commonly assigned U.S.Publication No. 2005/0119740 to Esch et al., now U.S. Pat. No.7,261,737, which is incorporated herein by reference. For completenessof disclosure, details of the IOL described in that application areprovided below.

IOL 20 comprises optic portion 21 and haptic portion 22. Optic portion21 is constructed of light transmissive materials, while haptic portion22 is disposed at the periphery of the optic portion and does notparticipate in focusing light on the retina of the eye.

Optic portion 21 comprises anterior lens element 23 including actuator24 (see FIG. 6), intermediate layer 25 and posterior lens element 27,also referred to herein as “substrate,” all made of light-transmissivematerials, such as silicone or acrylic polymers or other biocompatiblematerials as are known in the art of intraocular lenses. Illustratively,actuator 24 comprises a bellows structure that is integrally formed withanterior lens element 23. It will be appreciated that actuator 24 mayalternatively be integrally formed with intermediate layer 25, ifdesired. Optic portion 21 is illustratively described as comprisingthree layers, although it will be apparent that other arrangements maybe employed.

Anterior lens element 23, actuator 24 and intermediate layer 25 arespaced from each other and lens element 23 and intermediate layer 25 aresealably coupled at their circumferences to define cavity 34therebetween. Cavity 34 is filled with a fixed volume of shaping fluid.The shaping fluid is light-transmissive fluid, preferably silicone oracrylic oil or another suitable biocompatible fluid, and is selected tohave a refractive index that matches the materials of anterior lenselement 23, actuator 24, intermediate layer 25 and posterior lenselement 27. Furthermore, the viscosity of shaping fluid is selected sothat shaping fluid may be easily distributed within cavity 34 inresponse to relative motion between anterior lens element 23, actuator24 and intermediate layer 25.

Haptic portion 22 illustratively comprises haptics 28 and 29 that extendfrom substrate 26. Each of haptics 28 and 29 includes an interior volume30 that communicates with channel 31 in substrate 26. Actuator 24 isdisposed in well 32 formed in intermediate layer 25 and substrate 27, sothat a lower end of the actuator seats within well 32. Haptics 28 and 29may include resilient support members 33 (see FIGS. 5 and 6) that urgehaptics 28, 29 radially outward to ensure that haptics 28, 29 seatagainst the capsular equator and ensure that optic portion 21 remainscentered in capsule 15. It should be appreciated that support members 33need not form a portion of the structure of haptics 28, 29, but insteadmay be separate components that primarily ensure that optic portion 21remains centered, as will be described in further detail with referenceto additional embodiments below.

Although channel 31 and well 32 are depicted in FIG. 6 having their sidewalls disposed parallel to the optical axis of the lens, it is expectedthat all such surfaces may be arranged obliquely relative to the opticalaxis of IOL 20. Such an arrangement is expected to reduce the potentialto create spurious reflections in light passing along the optical axisof the IOL. It should be understood that such arrangements may bebeneficially employed throughout the IOLs described in thisspecification.

As depicted in FIG. 5, each of haptics 28, 29 has an undeformed stateand may be transitioned to a deformed state (shown in dotted line inFIG. 5) by application of compressive forces (shown by arrows C) to theanterior and posterior surfaces of haptic 28, 29. Haptics 28 and 29 areconfigured so that the interior volumes of the haptics increase as thehaptics deform from the undeformed, unstressed state to the deformedstate. The undeformed, unstressed state depicted by the solid lines inFIG. 5 corresponds to a fully-contracted state of the ciliary muscles,as described herein below.

Actuator 24 is disposed in well 31 of intermediate layer 25 andsubstrate 27, and preferably comprises a sturdy elastomeric material.Intermediate layer 25 and actuator isolate fluid in channel 31, well 32and the interior of actuator 24 from the shaping fluid disposed incavity 34. The fluid disposed within channel 31, well 32 and actuator24, preferably comprises silicone or acrylic oil or another suitablebiocompatible fluid, and is selected to have a refractive index thatmatches the materials of anterior lens element 23, actuator 24,intermediate layer 25 and posterior lens element 27.

Illustratively, actuator 24 comprises a bellows structure integrallyformed with anterior lens element 23, and is configured to deflectanterior lens element 23 responsive to fluid pressure applied within thebellows by haptics 28, 29. Alternatively, actuator 24 may be fabricatedas a separate component and glued or otherwise bonded to anterior lenselement 23 and intermediate layer 25.

Deflection of the anterior lens element resulting from movement ofactuator 24 causes the anterior lens element to transition between anaccommodated state, in which the lens surface is more convex, to anunaccommodated state, in which the lens surface is less convex. As willof course be understood, optic portion could instead be arranged so thatactuator 24 deflects posterior lens element 27. Still further, theactuator may be configured to induce a major deflection of one lenselement and a minor deflection of the other lens element; thearrangement depicted in FIG. 4 is intended to be illustrative only.

The inner surface and thickness of anterior element 23 (relative to theoptical axis of the lens) are selected so that the outer surface ofanterior lens element 23 retains an optically corrective shapethroughout the entire range of motion of actuator 24, e.g., foraccommodations 0-10 diopters. It should of course be understood that theinner surface and thickness of anterior element 23 may be selected toprovide an aspherical outer surface in combination with the deformingcharacteristics of the shaping fluid within cavity 34 of the presentinvention, as required for a desired degree of optical correction.

While IOL 20 includes a single actuator 24 located at the center ofoptic portion 21, the IOL alternatively may include an array ofactuators spaced apart in any predetermined configuration on theposterior surface of the anterior lens element, as may be required toimpose a desired pattern of localized deflection on the anterior lenselement. As will be apparent to one of skill in the art, an annularstructure may be substituted for the individual actuator depicted inFIG. 5, and the side walls of the actuator may be of any suitable shapeother than a bellows structure. For example, the actuator may comprise apolymer that had been treated, such as by application of bi-axialstress, to pre-orient the polymer to stretch predominantly in a desireddirection.

IOL 20 also may include coating 35 disposed on all interiorfluid-contacting surfaces within IOL 20, such as fluid channel 31 andwell 32 and the surfaces defining cavity 34. Coating 35 is configured toreduce or prevent diffusion of the index-matched fluid used to driveactuator 24, and within cavity 34, from diffusing into the polymermatrix of the lens components and/or to prevent inward diffusion ofexternal fluids into the IOL. The IOL also may include coating 36, whichcomprises the same or a different material than coating 35, disposed onthe exterior surfaces of the lens. Coating 36 is intended to serve as abarrier to prevent the diffusion of fluids from the eye into the IOL orfrom the IOL into the eye, and may be disposed on the entire exteriorsurface of the optic portion and haptic portion, including the anteriorand posterior lens elements and haptics.

Alternatively, both coatings 35 and 36 may be layered onto a singlesurface to prevent or reduce both ingress of bodily fluids into the IOLor fluid circuit, and loss of index-matched fluid from the interiorspaces of the IOL. Coatings 35 and 36 preferably comprise a suitablebiocompatible polymer, perfluorinated hydrocarbon, such as PTFE,inorganic (e.g., silicone dioxide) or metallic layer (e.g.,nickel-titanium) applied by any of a variety of methods known in theart.

Operation of IOL 20 of FIGS. 4-6 is now described. IOL 20 is implantedwithin a patient's capsule after extraction of the native lens using anysuitable technique. When implanted, haptics 28 and 29 support the IOL sothat optic portion 21 is centered along the central axis of eye. Whenthe ciliary muscles are in a contracted state, the zonules and capsuleare less taut, and the haptics 28 and 29 are in the undeformed state. Inthis condition, fluid pressure applied by the fluid in the haptics,channel 31 and well 32 maintain actuator 24 fully extended, so thatanterior lens element 23 is deflected to its accommodated state.

When the ciliary muscles relax, the zonules pull the capsule taut,thereby applying compressive forces on the anterior and posteriorsurfaces of haptics 28, 29. These forces cause haptics 28, 29 to deformto the deformed state depicted by the dotted lines in FIG. 5, therebyincreasing interior volume 30 of haptics 29, 30. Because there is only apredetermined amount of fluid contained within the interior of haptics28, 29, channel 31, well 32 and actuator 24, the increased interiorvolume 30 in deformed haptics 28, 29 draws fluid from within actuator24. This in turn causes actuator 24 to shorten, thereby deflectinganterior lens element 23 to a less convex, unaccommodated state.Subsequent contraction and relaxation of the ciliary muscles causes theforegoing process to repeat, thereby providing a degree of lensaccommodation that mimics the accommodating action of the natural lens.

As described above, spherical lenses may introduce sphericalaberrations. The inner surface and thickness of anterior element 23 maybe selected to provide an aspherical outer surface to lessen thespherical aberration through the lens. The present invention is directedto an IOL having another structural feature that alters the shape of thedynamic lens surface to further lessen the effects of sphericalaberrations.

Referring to FIGS. 7A, 7B and 7C, an embodiment of optic portion 41 ofan IOL constructed in accordance with the principles of the presentinvention is described. Optic portion 41 includes anterior lens element43, intermediate layer 45, actuator 44 and substrate 46. In the presentembodiment, intermediate layer 45 is integral with actuator 44. Similarto the above-described embodiment, the components of optic portion 41are made of light-transmissive materials, such as silicone or acrylicpolymers or other biocompatible materials as are known in the art ofintraocular lenses.

Actuator 44 includes projection 47 and flexible wall 48 thatcircumscribes projection 47. Wall 48 forms a generally annularundulation, or corrugation, and extends between a substantiallystationary portion of intermediate layer 45 and projection 47. Similarto the above-described embodiment, actuator 44 is in fluid communicationwith deformable haptics (not shown) that are used to distribute a fluidbetween the haptics, channel 51 in substrate 46 and well 52 that islocated adjacent actuator 44.

Deformation of the haptics by action of the ciliary muscles causes theinterior volume of the haptics to change, which may either force fluidthrough channel 51 toward well 52 or draw fluid through channel 51 fromwell 52. Forcing fluid into well 52 causes the fluid pressure withinwell 52 to increase, which increases the force placed on actuator 44. Anincrease in pressure in well 52 causes projection 47 to translate in ananterior direction. Conversely, when fluid is drawn from well 52,pressure within well 52 decreases and projection 47 translates in aposterior direction. In the present embodiment, translation ofprojection 47 is permitted by flexing of the wall of actuator 44adjacent projection 47. Projection 47 is coupled to anterior lenselement 43 so that movement of projection 47 causes anterior lenselement 43 to deform.

Anterior lens element 43 and intermediate layer 45 are coupled to eachother at their circumferences to provide a fluid seal 42 between the twocomponents. As a result of fluid seal 42, fluid cavity 50 is formedbetween anterior lens element 43 and intermediate layer 45. Anteriorlens element 43 and intermediate layer 45 may be coupled by adhering,welding or any other technique recognized in the art for creating afluid seal. For example, in an embodiment, an index-matched adhesive,such as an acrylic monomer, couples anterior lens element 43 andintermediate layer 45. However, it will be appreciated that anybiocompatible adhesive may be employed.

Fluid cavity 50 is filled with a substantially fixed volume of shapingfluid. Coatings may be applied to the surfaces of cavity 50 to reduce orprevent diffusion of the shaping fluid from cavity 50.

For the purpose of further discussion, optic portion 41 will bedescribed with reference to boundary zone 55, outer peripheral zone 56,inner peripheral zone 57 and central zone 58. Boundary zone 55 islocated the furthest radially outward from the optical axis of opticportion 41 and includes the sealed coupling between anterior lenselement 43 and intermediate layer 45. Boundary zone 55 includes aportion of cavity 50 located the furthest radially outward from theoptical axis and fluid seal 42.

Outer peripheral zone 56 is located adjacent and radially inward fromboundary zone 55. Outer peripheral zone 56 of optic portion 41 includesa large portion of intermediate layer 45 and cavity 50. In the presentembodiment, anterior lens element 43 has a reduced thickness and isflexible in outer peripheral zone 56. In addition, the anterior surfaceof intermediate layer 45 may be generally concave so that it curves awayfrom anterior lens element 43, thereby forming an enlarged region ofcavity 50 and an enlarged space between anterior lens element 43 andintermediate layer 45.

Inner peripheral zone 57 is located adjacent and radially inward fromouter peripheral zone 56. Inner peripheral zone 57 includes a portion ofcavity 50 that is located between anterior lens element 43 and wall 48of actuator 44.

Central zone 58 is located further radially inward from inner peripheralzone 57. The optical axis of optic portion 41 extends through centralzone 58 and central portion of anterior lens element 43 and projection47 are disposed within central zone 58.

As described above, deformation of the haptics by action of the ciliarymuscles and capsule causes the interior volume of the haptics to change,thereby causing actuator 44 and anterior lens element 43 to move. Theportions of cavity 50 within each of boundary zone 55, outer peripheralzone 56, inner peripheral zone 57 and central zone 58 each have a firstvolume when optic portion 41 is in the unaccommodated state shown inFIGS. 7A and 7B. When movement of actuator 44 and translation ofprojection 47 causes optic portion 41 to transition to the accommodatedstate, shown in FIG. 7C, there is a resultant change in the shape ofcavity 50 and each of the portions of cavity 50 experiences a change toa second volume.

During the transition of optic portion 41 from the unaccommodated stateto the accommodated state, the total volume of cavity 50 remainsconstant, but the volume of portions of cavity 50 may change. Inparticular, the volumes of the inner peripheral and central portions ofcavity 50 generally increase as projection 47 translates and forcesanterior lens element 43 anteriorly. The increase in volume of thoseportions causes the shaping fluid contained within cavity 50 to be drawninto that increased volume from the outer peripheral and boundaryportions of cavity 50. As the shaping fluid is drawn from those outerportions, it reduces pressure in those outer portions of cavity 50, thuscausing the outer portions of anterior lens element 43 to be drawntoward intermediate layer 45, as shown in FIG. 7C, thereby reducing thevolume of those portions.

The shape of cavity 50 and resulting changes in volume of the variousportions of cavity 50 result in the central and inner peripheralportions of anterior lens element 43 being generally more convex thanthe boundary and outer peripheral portions of cavity 50. It will beappreciated that the boundary and outer peripheral portions of anteriorlens element 43 may be convex, concave or flat as desired because due tothe stopping down of the pupil and/or the Stiles-Crawford Effect lightpassing through those portions may be less significant for propervision.

It should be appreciated that the shape of cavity 50 may be selected bycreating intermediate layer 45 and anterior lens element in any desiredshape and thickness. The shapes and thicknesses of those components maybe used to create any desired changes in the volumes of the variousportions of the cavity 50 and to create any desired pressure changesduring movement of actuator 44. Furthermore, the change in volume of thevarious portions of cavity 50 may be controlled by adjusting theelasticity of each of the corresponding portions of anterior lenselement 43, intermediate layer 45 and actuator 44.

It should also be appreciated that the boundary condition, i.e., theconfiguration of the interface of intermediate layer 45 and anteriorlens element 43 may be selected to create relative motion between thosecomponents in boundary zone 55. For example, as shown in the presentembodiment, anterior lens element 43 and intermediate layer 45 may berigidly fixed so that there is no relative movement between thecomponents at the location of fluid seal 42 between the parts.Alternatively, the sealed coupling between anterior lens element 43 andintermediate layer 45 may be configured to allow limited relative motionbetween the parts. For example, fluid seal 42 may include a bellows orhinge member that allows relative motion.

Referring now to FIGS. 8A and 8B, an embodiment of an IOL constructed inaccordance with the principles of the present invention is described.IOL 60 utilizes a sealed cavity 70 and shaping fluid to create anaspherical accommodated lens. Additionally, IOL 60 includes backstops 73for maximizing the hydraulic forces generated by asymmetric loadsimposed during transition of the lens capsule between the accommodatedand unaccommodated states. IOL 60 generally includes optic portion 61and haptic portion 62, both of which are similar in construction to thecorresponding portions of the embodiment of FIGS. 4-6. In particular,optic portion 61 includes anterior lens element 63, actuator 64,intermediate layer 65 and substrate 66.

Haptic portion 62 includes haptics 68, 69, each of which definesinterior volume 67 that is in fluid communication with channel 71 andwell 72 formed in substrate 66. Because the structure of the componentsis substantially identical to the corresponding structures of IOL 20described above, these components will not be described in furtherdetail.

In accordance with the principles of the present invention, IOL 60further comprises cavity 70 which is a fluidly sealed cavity defined byanterior lens element 63 and intermediate layer 65. Cavity 70 contains asubstantially fixed volume of shaping fluid. Which is distributedthrough cavity 70 when actuator 64 forces anterior lens element 63 tomove under the influence of haptic portion 62.

In the present embodiment, intermediate layer 65 is a separate componentfrom actuator 64 and as a result, a fluid seal is provided both betweenanterior lens element 63 and intermediate layer at the periphery ofoptic portion 61 as well as between intermediate layer 65 and actuator64 near the center of optic portion 61.

IOL 60 further comprises backstops 73 that rigidly support at least aportion of the circumference of each of haptics 68 and 69. Backstops 73are coupled to a portion of the outer surface of each haptic 68, 69 andare cantilevered members that generally follow the substantiallytoroidal shape of haptics 68, 69.

The present embodiment combines the shaping fluid included in cavity 70and backstops 73 to more efficiently convert movement of a lens capsuleinto hydraulic forces in IOL 60 and to prevent or reduce resultingspherical aberration.

Referring now to FIGS. 9A and 9B, an alternative embodiment of an IOLconstructed in accordance with the principles of the present inventionis described. IOL 80 generally includes optic portion 81 and hapticportion 82, both of which are similar in construction to thecorresponding portions of the embodiments described above. Inparticular, optic portion 81 includes anterior lens element 83, actuator84, intermediate layer 85 and substrate 86.

Haptic portion 82 includes haptics 88 and 89, each of which defineinterior volume 87 that is in fluid communication with channels 91 andwell 92 that are formed in substrate 86. Because the structure of thecomponents is substantially identical to the corresponding structures ofthe previously described embodiment these components will not bedescribed in further detail.

IOL 80 also includes sealed cavity 90 that contains shaping fluid. Asdescribed above, movement of actuator 84 and anterior lens element 83causes changes in the volumes of portions of cavity 90 which in turncauses the shaping fluid to be redistributed within cavity 90. Theredistribution of the shaping fluid causes changes in pressure withincavity 90 which causes further deflection of anterior lens element 83generally to an aspheric shape.

Backstops 93 also are provided in IOL 80, and extend from optic portion81 to haptics 88 and 89. Backstops 93 are generally shaped as sectionsof a disk or cone. Similar to the backstops described with regard to theprevious embodiment, backstops 93 provide support to a portion ofhaptics 88, 89 so that movement of the lens capsule is more efficientlyconverted into deformation of haptics 88, 89 rather than intotranslation of haptics 88, 89.

Referring to FIGS. 10A and 10B, an additional embodiment of an IOLconstructed in accordance with the principles of the present inventionis described. Similar to the previously described embodiments, IOL 100generally includes optic portion 101 and haptic portion 102. Opticportion 101 includes anterior lens element 103, substrate 106 andactuator 104 interposed therebetween. In the present embodiment,actuator 104 also forms an intermediate layer and substrate 106 mayfunction as a posterior lens element.

In accordance with the present invention, IOL 100 includes a sealedcavity 110 that is formed between intermediate layer 105, actuator 104and anterior lens element 103. Cavity 110 is filled with a substantiallyconstant volume of shaping fluid that is redistributed through cavity110 when actuator 104 moves anterior lens element. Cavity 110 is fluidlysealed by a seal between anterior lens element 103 and intermediatelayer 105 formed by the circumferential coupling of those components.

Haptic portion 102 includes haptics 108 and 109, each of which definesinterior volume 100 that is in fluid communication with channels (notshown) and well 101 that are formed between actuator 104 and substrate106. Each haptic 108, 109 is integrated into substrate 106 and extendsbackstop portion 113 of substrate 106. Backstop 113 is configured toprovide support over a posterior portion of haptics 108, 109. It shouldbe appreciated that the dimensions of haptics 108 and 109 and backstopportion 113 are selected so that backstop portion 113 is significantlymore rigid than haptics 108, 109 so that haptics are permitted to deformwhen acted upon by the lens capsule.

Additionally, load shelf 114 is provided on an anterior portion of eachhaptic 108, 109 that is approximately diametrically opposed to backstop113. Shelf 104 includes anterior surface 115 that is configured toengage a portion of the anterior wall of a lens capsule. Anteriorsurface 115 provides a greater surface area upon which force may beexerted on haptic 108, 109 by the lens capsule. As a result, energy frommovement of the capsular bag may be captured more efficiently andconverted into deformation of haptic 109, 98 and hydraulic forces withinIOL 100.

The present embodiment also illustrates an alternative boundarycondition between anterior lens element 103 and intermediate layer 105.In particular, anterior lens element 103 includes an undulation similarto that of actuator 104 and a wall section of anterior lens element 103that is oriented in the anterior/posterior direction is coupled tointermediate layer 105. As a result of that wall section, the peripheralportion of anterior lens element 103 may be permitted to bend morefreely when actuator 104 deforms anterior lens element 103 andredistributes the shaping fluid within cavity 110.

Referring now to FIGS. 11A and 11B, an embodiment of an IOL constructedin accordance with the principles of the present invention is described.IOL 120 utilizes sealed cavity 130 and shaping fluid to create anaspherical accommodated lens while maximizing the hydraulic forcesgenerated by asymmetric loads imposed during transition of the lenscapsule between the accommodated and unaccommodated configurations. IOL120 generally includes optic portion 121 and haptic portion 122, both ofwhich are similar in construction to the corresponding portions of theembodiments described above. In particular, optic portion 121 includesanterior lens element 123, actuator 124, intermediate layer 125 andsubstrate 126.

Haptic portion 122 includes haptics 128, 129, each of which defineinterior volume 127 that is in fluid communication with channels 131 andwell 132 that are formed in substrate 126. Because the structure of thecomponents is substantially identical to the corresponding structures ofthe embodiments described above, these components will not be describedin further detail.

IOL 120 also includes capsule support members 135 that are locatedexternal of haptics 128, 129. Support members 135 are tab-shapedfeatures that extend radially outward and are configured to engage theinner wall of a lens capsule so that the capsule is held in a more tautconfiguration so that engagement between haptics 128, 129 and the lenscapsule is maintained when the ciliary muscles are relaxed orcontracted. Maintaining that engagement more efficiently convertsmovement of the lens capsule to deformation of haptics 128, 129. Supportmembers 135 are preferably located adjacent to the coupling of haptics128, 129 to optic portion 121, because deformation of that portion ofhaptics 128, 129 is not relied upon for moving fluid in IOL 120. Itshould be appreciated however that support members 135 may be locatedanywhere that will not prevent haptics 128, 129 from deformingsufficiently to transition optic portion 121 between the accommodatedand unaccommodated configurations.

Referring now to FIG. 12, an embodiment of an IOL constructed inaccordance with the principles of the present invention is described.IOL 140 utilizes a sealed cavity and shaping fluid to create anaspherical accommodated lens while maximizing the hydraulic forcesgenerated by asymmetric loads imposed during transition of the lenscapsule between the accommodated and unaccommodated configurations. IOL140 generally includes optic portion 141 and haptic portion 142, both ofwhich are similar in construction to the corresponding portions of thepreviously described embodiments.

The present embodiment illustrates an alternative construction ofsupport members 145. Support members 145 are generally wires thatcircumscribe haptic portion 142 radially outward from each of haptics148, 149. Each support member 145 is preferably coupled to hapticportion 142 where each of haptics 148, 149 is coupled to optic portion141.

Support members 145 are configured to engage the inner wall of a lenscapsule so that the capsule is held in a more taut configuration so thatengagement between haptics 148, 149 and the lens capsule is maintainedwhen the ciliary muscles are relaxed or contracted. Maintaining thatengagement more efficiently converts movement of the lens capsule todeformation of haptics 148, 149.

In addition to utilizing the sealed cavities containing a fixed volumeof shaping fluid, the flexibilities and shapes of the components may beselected to tailor the influence of the shaping fluid. In particular,the thickness and material of the anterior lens component may beselected to provide a desired deflection. In addition, the shape of thesealed cavity may be selected by altering the shapes of the adjacentcomponents to provide any desired change in volume for any portion ofthe cavity.

It should be appreciated that although each embodiment has beendescribed having one sealed cavity, any number of sealed cavitiescontaining shaping fluid may be included. For example, sealed cavitiesmay be included adjacent to any desired portion of the lens element sothat discrete portions of the lens element may be shaped in a desiredfashion.

While preferred illustrative embodiments of the invention are describedabove, it will be apparent to one skilled in the art that variouschanges and modifications may be made therein without departing from theinvention. The appended claims are intended to cover all such changesand modifications that fall within the true spirit and scope of theinvention.

What is claimed is:
 1. An accommodating intraocular lens, comprising: anoptic portion including an anterior lens element, a posterior surface,and an optic fluid chamber, the anterior lens element comprising asecondary deflection mechanism that includes a portion of the anteriorlens element with a variable thickness; a haptic with a haptic fluidchamber in fluid communication with the optic fluid chamber; a fluiddisposed in the optic fluid chamber and the haptic fluid chamber;wherein the anterior lens element is adapted to deform in response tomovement of the fluid between the haptic fluid chamber and the opticportion fluid chamber; and wherein the second deflection mechanismdeforms the anterior lens element to an aspheric shape in response tomovement of the fluid from the haptic fluid chamber to the optic fluidchamber.
 2. The accommodating intraocular lens of claim 1, wherein thehaptic has an oval configuration.
 3. The accommodating intraocular lensof claim 1, wherein the haptic has a proximal portion secured to theoptic portion and a free distal portion disposed away from the proximalend, wherein a radially innermost surface of the haptic, from theproximal portion to the free distal portion, follows a curvedradially-outermost peripheral surface of the optic portion.